It is clear that new regulations are quite strict for new engines. But what happens to older equipment which still have a long life ahead of them but are large sources of NOx and PM emissions? Due to this question, a growing number of remarkable retrofit projects all over the world have been, and will continue to be, implemented. Some of them are heading towards labor protection and others for environmental causes, these are the most relevant issues to be solved in this regard. For example:
- There are regulations for heavy duty/on-road vehicles in London (the “LEZ” Low Emission Zone), the “Milieu Zones” in Germany, Denmark and in the Netherlands.
- In the US, the retrofit of school buses has become a common practice. The idea behind it is to ensure that children will not suffer future consequences from these vehicle's emissions;
- In South America, Chile has implemented a retrofit project for its urban bus fleets. There, the altitude was a decisive matter - it increases the harmful effects caused by diesel emissions, which are already at high concentrations;
- Worldwide labor regulations, concerning heath protection, mostly require the use of wall flow filter systems for vehicles in tunnels, halls, and other poorly ventilated areas like mines;
- In Asia it is no different. As the economy grows, environmental problems arise. Retrofitting and adopting similar standards as the US and the EU are becoming more and more common.